Create a sun, spin some asteroids around it, and watch them collide and form planets.
This is a Multithread N-Point Gravity Simulator for PC and Android.
An N-Point Gravity Simulator is a realistic simulation in which all points attract each other: even the smallest asteroid has its own gravitational field that can affect even a large sun far away from it.
Can be reused as a library for making games.

PC (Multiplatform, Java)
Android (4.0.3 and up, x86 and ARM)

Demo: GNU GPL Version 3 or newer
As library: GNU LGPL Version 3 or newer